The investigators have found a linear correlation of the modest increases in the blood lead urban children with a decrease in Na/K ATPase activity of the red cell (rbc) membrane. Na/K ATPase activity in known to relate to membrane permeability and cell survival and our preliminary data shows an increase in red cell enzymes consistent with decreased red cell survival (NIH-NIEHS 802043 and ES 0093901). The proposed study investigates the health effects of low level lead relating to a decrease in rbc membrane Na/K ATPase: 1) decreased rbc survival as reflected by increases in the rbc hexokinase, glutamic oxalacetic transaminase, and aldolase; 2) increased net efflux of K ion from the rbc (simultaneous assays of Na/K ATPase and K ion efflux in response to lead have never been documented); 3) altered osmotic fragility. The correlation of these health effects with Na/K ATPase will be investigated in the following groups of 80 urban children, ages 3-14; 20 non-anemic; 20 iron deficient; 20 G-6-PD deficient; 20 with sickle cell trait. It is proposed that the decrease in rbc Na/K ATPase associated with low level lead is a significant health effect. In the common nutritional and genetic disorders of the red cell, the increased environmental exposure to lead may further decrease red cell survival.